Synthesis of a 2-nitroimidazole derivative N-(4-[18F]fluorobenzyl)-2-(2-nitro-1H-imidazol-1-yl)-acetamide ([18 F]FBNA) as PET radiotracer for imaging tumor hypoxia
Bibliographic record
Abstract
Abstract Background Tissue hypoxia is a pathological condition characterized by reducing oxygen supply. Hypoxia is a hallmark of tumor environment and is commonly observed in many solid tumors. Non-invasive imaging techniques like positron emission tomography (PET) are at the forefront of detecting and monitoring tissue hypoxia changes in vivo. Results We have developed a novel 18 F-labeled radiotracer for hypoxia PET imaging based on cytotoxic agent benznidazole. Radiotracer N -(4-[ 18 F]fluorobenzyl)-2-(2-nitro-1H-imidazol-1-yl)acetamide ([ 18 F]FBNA) was synthesized through acylation chemistry with readily available 4-[ 18 F]fluorobenzyl amine. Radiotracer [ 18 F]FBNA was obtained in good radiochemical yields (47.4 ± 5.3%) and high radiochemical purity (> 95%). The total synthesis time was 100 min, including HPLC purification and the molar activity was greater than 40 GBq/µmol. Radiotracer [ 18 F]FBNA was stable in saline and mouse serum for 6 h. [ 18 F]FBNA partition coefficient (log P = 1.05) was found to be more lipophilic than [ 18 F]EF-5 (log P = 0.75), [ 18 F]FMISO (log P = 0.4) and [ 18 F]FAZA (log P = − 0.4). In vitro studies showed that [ 18 F]FBNA accumulates in gastric cancer cell lines AGS and MKN45 under hypoxic conditions. Conclusions Hence, [ 18 F]FBNA represents a novel and easy-to-prepare PET radioligand for imaging hypoxia.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".